Electric switch



April 3, 1951 W. SHARP ELECTRIC SWITCH Filed April 14, 1949 9 Jill Invenlor M sun/91 Patented Apr. 3, 1951 ELECTRIC SWITCH William Sharp,Birmingham, England Application April 14, 1949, Serial No. 87,443 InGreat Britain May 4, 1948 (C1. 2il0116) 3 Claims.

as spring member for opening the switch arm,

thus avoiding the use of independent springs and the possibility of theswitch not opening by breakage of springs.

A further object of the invention is the provision of means making useof the construction of a thermostatically operated catch which is heldin the catch position by the spring member .forming the moving contacts.

A still further object of the invention is to provide means leading to asimple form of thermostatically operated catch release coacting directlywith the switch arm.

Referring to the drawings:

Figure 1 is a plan of the switch body with the switch arm opened out.

Figure 2 is a section on line IIII of Figure 1, but showing the switchclosed and showing the switch casing in broken lines.

Figure 3 is a side elevation of the switch body.

Figure 4 is a plan View of the catch on the switch arm.

According to a convenient embodiment of this invention, the switchcomprises a rectangular insulating base I which has three parallelchannels 2 formed thereacross. A spring contact blade 3 is mounted ineach channel at one end and each contact blade comprises a Z-shaped,strip of spring metal Which is fixed to the base I and has a circuitmains terminal 4 thereon for fixing thereto a lead wire of the electricsupply. The spring contact blade 3 is conveniently formed of Phosphorbronze. The fixed contacts 5 comprise metal strips fix d inside thechannels 2, one end of the strip being L-shaped to form a raised stepfor contacting with the spring contact blade 3. One arm of an L-shapedbi-metal strip 6 is fixed under each contact strip 5 by means of theterminal screw I which fixes the contact strip 5 to the base I, Aheating wire 8 is coiled around an insulating sleeve 9 on the bi -metalstrip, and one end of this wire 8 is connected to a circuit mainsterminal Iii for a lead wire of the electric motor circuit and to thecontact strip 5 by the screw 1. The switch arm I I is mounted onbifurcated lugs I2 on each side of the insulating base I, and such armhas three projections I3 adapted to bear on the spring contact blades 3and press the same on the fixed contacts 5. A trip catch lever I4 ispivotally mounted on the base and comprises a U-shaped Wire memberhaving an insulating sleeve thereon for contacting with the bi-metalstrips 6. The trip catch lever is normally urged inwardly towards thebi-metal strips 6 by the spring I5. The switch arm has an adjustablecatch projection I B which when the switch arm is being closed isadapted to bear against the roller on the trip catch lever and press itrearwardly so that the trip catch lever will engage over the projectionI and hold the switch arm in the on position. The base I is mounted in abox I! and two plungers or press buttons I 8 and I9 are mounted on thecover 20, one plunger I9 being adapted to bear on the switch arm II toclose the switch, whilst the other plunger I8 when depressed bearsagainst and pivots the trip catch lever I 4, so that the switch arm willautomatically open by the pressure of the contact blades 3. The tripcatch lever can also be moved by the bi-meal st i s. If the bi-metalstrip is overheated it is deflected against the trip catch lever I l andmoves the same from the proiection, thereby throwin the switch ooen. Byadjusting the proiection IS, the particular condition when the switchwill automatically open can be varied.

In order to prevent the switch being closed until the bi-metal stripshave assumed their normal rosition, a stop lever 2! is pivoted on thebase I and. connected by the helical spring 22 to the trip catch leverI4. When therefore the trip catch lever I 4 is moved by the bi-metalstrips, the lever 2i will be pivoted therewith to lie in the path of aprojection 23 on the arm I I, th reby prev nting such arm beingdepressed. The spring 22 forms an expansible link and permits the catchlever I4 to be moved to engage over the projection l6 whilst theproiection 23 lies in front of the lever 2|. The coils of the spring arenorma ly closed to form a solid link to push the lever 2I rearwardly bythe spring pressure of the lever I-I.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent, is:

1. An electric switch comprising an insulating base, a plurality offixed contacts on the base, each fixed contact being electricallyconnected to a circuit mains terminal, a plurality of movable contactsmounted on the base and each comprising a blade spring forming an armflexibly connected at one end to said base, each blade aseaeoa springforming an electric conductor and bein electrically connected to anothercircuit mains termi al, a s itc a m ni otallv mounted on said base andro i ed with roiect ons da ed to bear against said arms of the m ablecontacts and to de r ss the said. movabl contacts into contact with thesaid fi ed contacts. said movable contacts b in adapted to be ur ed. toopen osition hv the spr ng n s re of the sai mov bl conta ts on said r jctions. a tri lever compri ing a transve se bar having le s at each sidewhich are nivot llv mo nted on said base a catch proj ction on t epivoted switch, arm which is engage b the trio lever and held in en aement by said b ade sp ings, bi-metal strips which lie in front of sa dtransverse bar and which when deflected pivot the trip lever to releasesaid switch arm when an overcurrent passes through one or more of thebi-metal strips, a first press button adapt d to bear on said switch armto thereby move said catch proection into engagement with the trip leer. and a second press b tton adapted to bear against and operate thetrip lever to release the switch arm.

2. An electric switch com rising an insulating base, a plurality offixed contacts on said base, each fixed contact being electricallyconnected to a circuit mains terminal, a plurality of movable contactsmounted on the base and each movable contact comprising a Z-shaped bladespring having a straight arm and a double-bend at its inner end forconnection to the base and forming an electric conductor andelectrically connected to another circuit mains terminal, a switch armpivotally mounted on said base and provided with projections adapted tobear against said arms of said movable contacts and to depress saidmovable contacts into engagement with said fixed contacts and by flexingsaid straight arms inwardly between said fixed contacts and thedouble-bend at the fixed ends of the blade springs and to be urged inthe open position by the spring pressure of said movable contacts onsaid switch arm projections, a trip lever comprising a transverse bararranged parallel to the axis of said switch arm and having legs at eachside which are pivotally mounted on said base, a catch projection on thepivoted switch arm which is engaged by said transverse bar of the triplever and held in engagement by said blade springs, one or more bi-metalstrips lying in front of the said transverse bar and adapted to defiectand to thereby pivot the trip lever to release said switch arm when anovercurrent passes through one or more of said bimetal strips, a firstpress button adapted to bear on the switch arm to thereby move the catchprojection into engagement with the trip lever,

4 and a second press button adapted to bear on the transverse bar of thetrio lever for moving the same to release the switch arm.

3. An electric switch comprising an insulating base, a plurality offixed contacts on the base, each fixed contact being electricallyconnected to one circuit mains terminal, a plurality of movable contactsmounted on the base, each movable contact comprising a blade s ringshaped to form a straight arm and a double-bend at its inner end forconnection to the base and forming an electric conductor connected toanother circuit mains terminal, a switch arm pivotally mounted on saidbase and provided with projections adapted to bear against said straightarms of said movable contacts and to depress said movable contacts intocontact with said fixed contacts and by flexing the straight armsinwardly between the fixed contacts and the double-bend at the fixedends of the spring blades and to be urged in the open position by thespring pressure of said blade springs of the movable contacts on saidprojections, a trip lever comprising a transverse bar'arrangedsubstantially parallel to the axis of said switch arm and having lugs ateach side which are pivotally mounted on said base, a catch projectionon the pivoted switch arm which is engaged by said transverse bar of thetrip lever and held in engagement by said spring blades, bi-metal stripslying in front of said transverse bar of the trip lever and adapted todeflect to thereby pivot the trip lever for release of the switch armwhen an overcurrent passes through at least one of said bimetal strips,a first press button adapted to bear on the switch arm to move saidcatch projection into engagement with the trip lever, a second pressbutton adapted to bear on the transverse bar of the trip lever formoving the same to release the switch arm, and a stop device comprisinga pivoted lever connected to said bi-metal strip by means of a helicalspring, so that when said bi-metal strip is flexed by overload current,said pivoted lever is moved into position to form a stop preventing thepivoted switch arm being moved into the on position until said bi-metalstrip assumes its normal position.

' WILLIAM SHARP.

REFERENCES CETED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,215,665 Landis Feb. 13, 19171,893,827 Getchell Jan. 10, 1933 2,013,013 Van Valkenburg Sept. 3, 1935

